The name Betsy is a girl's name of Hebrew origin meaning "pledged to God". Betsy and is often added to lists like Nicknames for Elizabeth and discussed in our forums with posts like "Girls Makeover - Two Middles".
From the experts:
This Elizabeth nickname has a decidedly retro feel--think Betsy Ross and the Betsy Wetsy doll-- once seen as a perkier, younger-sounding alternative to Betty. But with Betty on the brink of a comeback, pigtailed Betsy could return as well.
Betsy's height of popularity was from the forties to the sixties, when she was likely to be the radio, film or TV teenaged daughter.